在其他类MFMailComposeViewControllerDelegate 4中未被调用

Question

我有这段代码，问题是didFinishWith结果没有被调用，应用程序崩溃了。这是我的密码

注释:在目标C中，这段代码运行良好，因为我在类中创建了一个强大的引用，但是我在Swift中遇到了一个问题，我不知道如何解决这个

import Foundation
import MessageUI

class EmailCreator: NSObject, MFMailComposeViewControllerDelegate {
    // in other class I send this var to show email
    var viewToShow = UIViewController ()

    func sendEmail() {

        let mailComposeViewController = createMailComposeViewController()
        if MFMailComposeViewController.canSendMail(){
            viewToShow.present(mailComposeViewController, animated: true, completion: nil)
        }else{
            print("Can't send email")
        }
    }

    func createMailComposeViewController() -> MFMailComposeViewController {
        let mailComposeViewController = MFMailComposeViewController()
        mailComposeViewController.mailComposeDelegate = self
        mailComposeViewController.setToRecipients(["example@test.test"])
        mailComposeViewController.setSubject("subject")
        mailComposeViewController.setMessageBody("test body", isHTML: false)
        return mailComposeViewController
    }
    //MARK: - MFMail compose method
    func mailComposeController(_ controller: MFMailComposeViewController, didFinishWith result: MFMailComposeResult, error: Error?) {
        controller.dismiss(animated: true, completion: nil)
    }
}

在其他课程中，我有这样的代码来显示电子邮件：

@IBAction func sendEmail(_ sender: UIButton) {

        let email = EmailCreator()
        email.viewToShow = self
        email.sendEmail()
}

Answer 1

它崩溃是因为您有一个EmailCreator，一个本地变量MFMailComposeViewController的委托，如您的func createMailComposeViewController中所示。当MFMailComposeViewController调用didFinishWith方法时，EmailCreator已经被deinit编辑了。您可以通过使您的EmailCreator实例成为一个强属性来解决这个问题。

YourViewController: UIViewController {
    let email = EmailCreator()

     @IBAction func sendEmail(_ sender: UIButton) {
        email.viewToShow = self
        email.sendEmail()
    }
}